Enforce all IO objects to be subclassed from Document (#88)

* enforce Document as IO

* Separate rerankers, splitters and extractors (#85)

* partially refractor importing

* add text to embedding outputs

---------

Co-authored-by: Nguyen Trung Duc (john) <trungduc1992@gmail.com>

knowledgehub/base/__init__.py

@@ -1,4 +1,25 @@
 from .component import BaseComponent
-from .schema import Document
+from .schema import (
+    AIMessage,
+    BaseMessage,
+    Document,
+    DocumentWithEmbedding,
+    ExtractorOutput,
+    HumanMessage,
+    LLMInterface,
+    RetrievedDocument,
+    SystemMessage,
+)
 
-__all__ = ["BaseComponent", "Document"]
+__all__ = [
+    "BaseComponent",
+    "Document",
+    "DocumentWithEmbedding",
+    "BaseMessage",
+    "SystemMessage",
+    "AIMessage",
+    "HumanMessage",
+    "RetrievedDocument",
+    "LLMInterface",
+    "ExtractorOutput",
+]